WALL GAIN LOAD
In determining the wall gain load, the heat gain through all the walls, including the floor and the ceiling, should be taken into account. When several walls or parts of walls are of different construction and have different U factors, the heat leakage through the different parts is computed separately.
Walls having identical U factors may be considered together, provided that the temperature differential across the walls is the same.
Where the difference in the value of U is slight and or the wall area involved is small, the difference in the U factor can be ignored and the walls or parts of walls can be grouped together for computation.
Wall gain load = A x U x TD
Where, A = outside surface area
U = wall gain factor
TD = temperature difference between the surroundings and the conditioned space.